1. Field of the Invention
The present invention relates generally to medical devices and methods of diagnosing or treating disease. More particularly, it concerns medical devices for use in delivery of therapeutic agents or diagnostic agents to cardiac valves, and methods for diagnosing or treating a disease of a cardiac valve in a subject using the same devices.
2. Description of Related Art
Valvular heart disease is a major cause of morbidity and mortality in the United States. The majority of these cases involve disorders of the aortic valve. Valvular disease of the aortic valve includes aortic stenosis, aortic regurgitation, and atresia of the aortic valve. Aortic valve stenosis results in approximately 65,000 aortic valve replacement surgeries each year in the United States.
Treatment for valvular heart disease depends on the type and severity of the diagnosis. There is no current effective treatment for individuals with minor valve problems. Those with more serious disease can be treated with therapeutic agents, such as ACE inhibitors, antiarrhythmics, antibiotics, anticoagulants, diuretics, and inotropic agents. Not uncommonly, oral therapeutic agent therapy is ineffective. Other therapeutic options are available, including mechanical dilation of the aortic valve (valvuloplasty), surgical repair of the valve, or valve replacement surgery may be needed. Each of these more invasive procedures is associated with a significant risk of complications. Patients with severe disease typically require surgical replacement of the valve. However, not all patients are treated with valve replacement, and medical therapy may be ineffective.
One of the limitations of oral therapeutic agent therapy of aortic valve disease is limited bioavailability of therapeutic agent at the site of disease (diseased valve leaflets) following oral administration. While dose of medication can be increased, such means for improving therapeutic agent delivery to the diseased valve tissue is limited because of the increased risk of toxic side effects. Various interventional methods for therapeutic agent delivery to aortic valves have been described in the literature. Generally, these devices are valvuloplasty devices. For example, U.S. Patent App. Nos. 2006/0229659 and 2005/0075662 describe valvuloplasty catheters and devices that can be designed for concurrent delivery of therapeutic agents in conjunction with valvuloplasty. The valvuloplasty procedures described therein involve the application of significant amounts of force on the aortic valve leaflets that in turn can cause restenosis of the valve or damage to the valve leaflets. Further, application of valvuloplasty with such devices carries with it a risk of significant disruption of valve function during valvuloplasty.